The invention relates to a hose for transporting abrasive material and in particular to a hose for transporting abrasive material having sensors for detecting wear of the hose.
A hose for transporting abrasive material, either fluidized or dry bulk, is usually constructed with an inner lining or tube made of abrasion resistant material, a carcass composed of layers of reinforcement plies to resist pressure within the tube and a rubber cover, typically of an elastomeric materials, to protect the carcass. The hose may include, a reinforcing steel wire helix embedded between the layers and a built-in coupling at each end.
Since the hose is used for transporting abrasive material, the inner lining and reinforcing layers of the hose can be worn through by the flow of the material during usage. Since the wear is within an internal section of the hose, it is not possible to visually inspect the degree of wear. The hose, if operated until total failure, can create unforeseeable and unwanted problems including leakage, rupture or explosion.
U.S. Pat. No. 4,446,892 (""892) by Maxwell discloses a fluid transport hose having two or more plies comprising a sensing element located between the plies, the sensing element being adapted to respond to the failure of an inner ply of the hose by presenting an open circuit. The purpose of the sensing element in the hose is to detect imminent breakdown of a hose section and to permit the user to replace the hose prior to external leakage. The ""892 patent also discloses a secondary sensing element disposed between the outermost plies of the hose to detect the occurrence of physical damage to the outer plies of the hose.
U.S. Pat. No. 5,634,497 (""497) by Neto discloses a hose for suction and discharge of abrasive material with a sensor circuit which indicates the total or partial wear of the inner lining of the hose, thus permitting hose replacement prior to its rupture or blow up. The ""497 patent discloses a sensing element comprised of a bi-polar (two-pole) socket fixed to one of the external layers of the hose and connected, preferably, to the terminal ends of wires which extend spirally along the entire length of the hose. In order to determine the wear of the hose, it is necessary to verify, by means of the bi-polar socket, the continuity of the sensing element. In the case where the sensing element is interrupted, this means that the wire wound within the hose has been broken, implying that the hose shows signs of internal wear and should be replaced.
It is an object of the present invention to provide an improved hose using a sensing system to detect the internal wear of a hose, as defined in one or more of the appended claims and, as such, having the capability of being constructed to accomplish one or more of the subsidiary objects.
It is another object of the present invention to provide a hose capable of transporting abrasive material, either dry bulk or fluid.
It is a further object of the present invention to detect wear of the hose without interrupting the transport of the abrasive material.
It is yet another object of the present invention to detect wear of the hose to avoid an operating accident such as leakage, rupture, and explosion.
It is still another object of the present invention to provide multiple levels of hose wear detection in order to permit hose reposition prior to replacement in order to maximize the hose""s useful life.
It is an object of the present invention to provide a hose with a wear-sensing element, which can be disposed within the tube or between the reinforcement plies of the hose using either wire or chemically sensitive tape.
In accordance with the invention, a hose for transporting abrasive material comprises first and second wear-sensing elements, one disposed at a first distance from the innermost surface of the inner lining (tube) and a second disposed at a second distance from the innermost surface of the inner lining (tube), the second distance being greater than the first distance. By monitoring the first and second wear-sensing elements with wear sensing devices, it is possible to detect wear of the inner lining and further wear as it propagates to one of the many layers disposed over (radially outward) the inner lining.
The first wear-sensing element is disposed adjacent to or within the inner lining (tube) or one of the reinforcement plies, running substantially the entire length of the hose. The first wear-sensing element, made up of a first set of two sensor wires, extends spirally over the length of the hose. One end of the first set of two sensor wires making up the first wear-sensing element are joined together. The other end of the first set of two wires making up the first wear-sensing element are connected to a first two-pole socket.
The second wear-sensing element comprises a second set of two sensor wires, each of the two sensor wires having one end extending to or even beyond one end of the hose and an opposite end extending to or even beyond the other end of the hose and joined (spliced) together. At the one end of the hose, the second set of sensor wires are connect to a second two-pole socket.
The means or structural components to detect wear is provided by connecting to the first and second two-pole sockets, through which the first and second wear-sensing elements can be monitored. Sensing wear at the first, innermost wear-sensing element permits the user to reposition the hose so as to continue operation until wear is sensed at the outermost second wear-sensing element, at which point the hose needs to be replaced prior to its failure during use. Repositioning the hose after sensing wear in the innermost layers of the hose extends the useful life of the hose.